S
M
T
W
T
F
S
26
81°
65°
27
84°
68°
28
81°
68°
29
80°
67°
30
85°
65°
31
79°
62°
1
79°
63°
2
80°
63°
3
79°
66°
4
81°
67°
5
85°
67°
6
79°
64°
7
83°
66°
8
85°
67°
9
84°
66°
10
85°
61°
11
83°
60°
12
80°
63°
13
79°
61°
14
81°
60°
15
79°
60°
16
79°
62°
17
77°
63°
18
78°
61°
19
77°
59°
20
78°
59°
21
78°
60°
22
81°
65°
23
80°
64°
24
83°
64°
25
83°
58°
26
82°
57°
27
76°
56°
28
75°
58°
29
75°
60°
30
76°
62°
31
75°
63°
1
80°
60°
2
76°
59°
3
78°
57°
4
75°
56°
5
74°
56°
Temperature Graph
°F
Avg. Hi
Avg. Lo
Actual Hi
Actual Lo
Forecast Hi
Forecast Lo
August Weather in Johnston
Johnston's August 2026 forecast shows daily high temperatures ranging from 74° to 85°, with overnight lows between 56° and 68°. The average high for August is 80° with an average low of 62°. AccuWeather's monthly forecast extends further ahead than any other source, with day-by-day RealFeel® Temperatures giving a complete picture of how August weather will actually feel in Johnston. See also: September | October | November.
